Fuse



Aug. 29, 1933. N. J. CONRAD FUSE Filed March l5 UNITED STATES PATENTorrica This invention relates to circuit interrupters .and moreparticularly to such interrupters as are particularly adapted for use onhigh voltage systems, although not limited to such systems. The 5circuit interruptor of the present invention is of the fused type, thatis it is one wherein the circuit is opened by the bl one of the objectsof the vide a device of this character which is exceedingly rapid in itsaction cal in construction.

In the embodiment described for illustrative purposes the invention isincorporated in a lfuse of the well known type comprising Ia. glass tubetallic ferrules at its opposite ends for establishing a circuit throughthe fuse within. A movable terminal member is mounted within thecontain-v er and adjacent one end thereof and a spring is provided forrapidly mo end upon the blowing o er is lled with an insulating liquidof high are extinguishing propertie drawn by the terminal member as itmoves under the action of the spring, thereby quickly extinguishing thearc. This the Schweitzer & Conrad fuse and one torni thereof is shown inthe United States patent to Edmond O. Schweitzer Number 1,135,548 issuedApril 13, 1915. however to be understood that the present invention isnot limited to such fuse structures but is .of general application.

In the fuse herein shown the upper ferrule is provided with a shoulderupon which a bridge member rests, and the fuse is suspended from thebridge member by means of a point suspension to allow for a universalmovement ofthe course understood that versal joint could be used ifdesired.

The movable system hich the fusefis conne is connected for supportingthe same. A spring holder is mounted on the terminal and is providedwith a helical groove coiled spring that pulls upwards on the lowerferr'ule. It is one of the objects of the present invention to provide an for supporting the terminal and a novel means for connecting thespring to the terminal. Another feature of novelty of the presentstructure resides in the means for connection between the rule.

.Nicholas .3'. Conrad, Winnetim, Ill., assigner, by mesne assignments,to Schweitzer da (Conrad, Inc., Chicago, Ill., a corporation of DelawareApplication March l5,- lllll.. Serial No. 436,@12 35 (lll. Ellie-117)within the fuse rises. owing of a fuse, and it is present inventionproand simple and economi-s When an arc is quenched by an insulatinglion uid, such as is here used, some of the liquid is voila- 'tilized bythe heat of the arc. occupies a greater volume than i liquid from whichit is genera or current flow bease of a very large c 1- rent new theamount of liquid volatilized may be of my 'invention herein or containerhaving nieving it towards the other f the fuse. The contain- Vent CED sinto which the arc is type of fuse is known as and Nicholas J. Conrad Itis To prevent the li suncient to shatter the fuse unless sonrie ineensis providedA for permitting the escape of the vapor, For this reason avent cap is provided, which vent cap blows when the pressure reaches c.predetermined value, that value being below that at which the glass' ofthe fuse would shatter.

Trie vent cap is sealed to the upper errule and it is one oi the objectsof the present invention to provide an improved means for sealing thequid .within the iuse from creeping outward along the joint between thecap and the upper ferrule I provide a seal consisting of plasticbaltelite or the like, and to prevent the entrance oi moisture into theiuse l provide an additional seal of asphaltum. bakelite constitutes theinner seal and the asphaltum the outer seal, whereby the prevents theliquid within the fuse from contacting with and attacking the asphaltum.

The attainment of the jects of the present invention will be apparentThe barette above and further obirom the following specication taken inconnec- Part thereof.

movable portion of the in the drawing! suspended parts. It is of anyother form of uniline 2-2 of Figure 1;

comprises a terminal to the vent cap removed;

cted and to which a Wire for receiving the end of a line 5 5 of Figurel.

ovel-and improved means establishing the electrical fuse and theupperferfluid tight closure.

Figure l is a longitudinal secti improved fuse structure;

Figure 2 is a sectional view taken along the Referring now more partieing, the fuse shown compr ends oi' which fit into the rules 2 and 3respectively, cured in position by a s which also serves as a pa tionwith the accompanying drawing forming a onal view of my Figure 3 is atop view of the fuse structure with Figure 4 is a fragmentary sectionalview taken along the line 1 -4 of Figure 2; and

Figure 5 is a sectional view taken along the ularly to the draw@ ises aglass tube 1 the upper and lower ierm the Ierrules being seuitable alloyfilling 4 cking for producing a While the tube shown is cylindrical inshape and is formed of glass it Sill may, if desired, be made of anyother suitable preventing 2 shape and likewise may be of any otherpreferred insulating material such as for example, ilber impregnatedwith bakelite or the like. The ferrules 2 and 3 are made of suitableconducting metal and constitute the terminals for making or breaking acircuit through the fuse. The upper and the lower ierrules are provided,on their inner side, with tapered or conical shoulders 6 forvcenteringthe tube 1 and for providing a minimum contacting area between the tubeand the ferrules. The top of the upper ferrule 2 has a cylindrical boreSi 'formed therein and terminating in a shoulder Si. Beyond the bore 8there is a cylindrical bore itl of reduced diameter, which boreterminates in e. shoulder il. The fuse mechanism as a whole is suspendedwithin the tube i. by means of an upwardly arched bridge i3 that restsupon shoulder Q. The bridge nie-roher fits snugly within the cyiindricalbore d and provided at its opposite ends with a pair of upwardlyextending projections lli-ifi which bear against the cylindrical wall ofthe bore ii, increasing the depth oi cooperation of the ends or thebridge member with the wall of the bore 8 and the bridge member fromworking up and out of its desired position in the bore 6. Theprojections 14 may ne made by merely stamping a small bulge in thebottom oi the bridge ,member at the ends thereof.

An inverted U-shaped bail member i6 extends through a central opening 17in the bridge meinber and is supported by a bridge bar i8 which restsacross the opening 17 in the bridge member 13 and which may be held inplace by means of a wire cotter pin 20. A very short pin 21 is securedto the bridge bar 18 and constitutes a single point support for the bailmember. A shallow spherical depression is formed in the bail member forproviding a seat for the bail member on the pin 2l. The bail member hascomplete freedom of motion on the supporting pin 21. The bail member 16constitutes a short length of copper tubing through which is passed ailexible braided wire 25, of copper or the like, and a strain wire 26 ofnichrome or the like, said wire having a high tensible strength and arather high electrical resistance. The end of a fuse 'wire 27 islikewise extended into the copper tube. The tube is then flattened in apunchpress or the like to firmly secure the braided wire 25, the wire 26and the fuse 27 in the tube. The fiattened tube is then bent to form anarch shape or U-shap'e member as shown in the drawing. A terminalassembly 30 is supported by the wire 26. The terminal 30 comprises aninternally threaded sleeve 3l and a cable securing member 32 secured inthe sleeve 31. The terminal 30 is made of brass or other suitablecurrent conducting material. The sleeve 3l has a s et of longitudinallyextending grooves 35l formed thereinl and has a hole 36 drilledtherethrough near the end of the sleeve.

The strani wire 26 is inserted in thc grooves 35, the ends of the wirebeing passed through the opening 36 in crossed relationship land thenagain extending into the grooves 35 onthe opposite sides of the sleevemember, a similar groove 36' is formed for receiving the end of the fuselink 27. The sleeve is then compressed in a punch press so as to causethe walls of the grooves to come together and firmly grip the ends ofthe wire 26 and the end of the fuse link 27 in the sleeve mem'- ber 30..A liquid director 40 is supported by the terminal 30 and for thispurpose it has three holes, 120 apart, formed therein. Through theseholes three pins or studs 42 are passed. These stds are freely movablewithin the holes in the sleeve member 31 and when they are fullylnserted within the sleeve the liquid director 40 may be passed over thesleeve. After the liquid director has been placed over the sleeve 3l ascrew 44 is threaded into the bore of the sleeve 3l. The screw 44 isprovided with a conical head 45 which forces the pins or studs Li2outward. The liquid director 40 has a groove i6 formed therein and therounded or spherical ends of the studs i2 enter this groove and therebysupport the liquid director in spacedrelationship to the terminal. Thecable terminal has an upper screw threaded portion 5o which. threadsinto the sleeve 3i. is thereby rigidly secured thereto and lower holiowportion into which a cable 53 oi material is rigidly secured. a.shoulder The portieri ci. the top of the sh r` 55 the lower Aostthreadof the threaded portion flatteN ed surfaces 56 as may be seen in Figure5, and the cable fastener has an opening of a similar As a result ofthis arrangement the spring fastener is held against rotation. There isa' loose ilt between the spring fastener 54 and the cable terminal 32,in order to permit a limited amount of side play between the two. Incaseof deflection of the spring fastener 54 laterally against the tube lthis play between the fastener 54 and the terminal member 32 willrelieve the tube of the inertia of the terminal member 32, to which itwould be subjected if the spring fastener and terminal 110 member wererigidly secured together. A helical groove is formed in the springfastener 54 and said spring fastener is threaded into a helical coiledspring 60. The lower end of the spring 60 is threaded around a springfastener 61 similar 115 to the spring fastener 54 and secured to orformed integral with a lower cable terminal 62. The lower ferrulev isprovided with an inwardly extending boss which is bored and internallythreaded to receive a threaded portion 66 on the 120 lower end of thecable terminal 62.

A washer 70 of bakelite or other suitable insulating material re'stsupon the shoulder 11 of the the cable tot upper ferrule and is providedwith a central opening through which the upper terminal 30 extends. 125The washer is of the split type and consists ofy two semi-circularhalves which lie in the boro l0 and embrace the top of theterminal 30after the terminal 30 has been assembled.

In assembling the fuse the spring 60 is first 130 threaded into thelower spring holder 61 and the upper spring holder 54 is then placedabove the upper cable terminal 36 and is threaded into the top oi thespring 6G and then lowered onto the shoulder 55. Thereafter the assemblycomprising the upper terminal 30 and the liquid director 40 are threadedonto the threaded portion 50. It is understood that at this time thespring is not under tension and therefore the two cable terminals aredrawn rather closely together. The 14o bail 16 is provided with suitabledepressions 72 and 'T3 formed therein for permitting the gripping of thebail memberby a tool whereby the same may be lowered into the tube 1.The mechanism is lowered until the threaded portion 66 145 on the lowercable terminal enters the bore in the boss 65 of the lower Ierrule. Thethreaded portion 66 is then threaded into the boss by means of asuitable tool. After this has been done the bail 16 is traised by meansof the sep- 150 liti arate tool gripping the bail at the depressions 72and 73, although other bail anchoring means may be employed and the bailis lifted until it extends through the opening 17 in the bridge member13. After the tube is filled with a suitableyarc quenching liquid thesplit collar 'lll and the bridge bar 18 are then inserted into place andthe bail 16 is thereafter lowered until it rests upon the bridge bar.The ilexiblebraided conductors 25 are previously inserted beneath theends ofthe bridge 13 so that the flexible conductor rests upon theshoulder 9 and in turn is pressed ,downward by the bridge member 13which seats thereon When the apparatus is in this position the spring isunder a rather great tension and thereby exerts a considerable pressureupon the bridge member 13 which pressure is transmitted through theflexible conductorr25 to the shoulder `9 thereby maintaining a ilrrnelectrical contact vbetween the flexible conductor -25 and the shoulder9. .Due to the fact that the bridge member 13 ts rather snugly withinthe ferrule, as previously stated, any` tendency on the part of thebridge member to collapse dovmwardly under the action of thespring 60will be resisted by the inner vertical wall-.of the ferrule and willresult in an increase in the pressure of the bridge member against theinner vertical ferrule wall. It is to be noted the pin 2l and the bail,16 provide a universal mounting for the terminal `member 30. Theuniversal mounting support permits free movement of the terminal member3o in all directions. It enables elimination ci guide prongs or the likeand it eliminates possibility of lszinking of the fuse or strain wiresuch as might occur with a rigid anchor at the upper end.

The are extinguishing liquid is preferably inn troduced into the tube ibefore the split collar 'lo is set in place.

The liquid within the tube is of hielo arc quenching properties. Anysuitable insulating liquid may be used. This insulating: liquid maycomprise carbon tetra-chloride-or any of the in-n sulating liquidsmentioned in the United States patent to Edmund 0. Schweitzer andNicholas J. Conrad, No. 1,3ii19o7 of October 2o, lele, although anyother preferred insulating liquid may be used.

il vent cap 3u is then mounted on. the top or? the upper ier'rule inorder to close the top of the fuse. The cap ed is secured to the outsideof the ierrule and is provided with an inclined shoulder 8i whichoverlies the ferrule. The can is seu cured to theV top oi the ferrule bya suitable ce ment which, although it may take other forms, preferablyconsists of a rim ot plastic bakelite the like interposed between thevent cover and the sides of the ferrule as indicated at e2. Thissubstance prevents the egress of the insulating .liquid within the tubeby creepage along the sides ci the lierrule. lin order to prevent theentrance of moisture into the tube there is further inter= posed betweenthe vent .cap and the ierrulea loyer of suitable cement impenetrable towater. This cement .is indicated at 83 and may consist of esplialturn orthe like.

The asphaltum is provided due to the i'act that moisture can creep intothe fuse through the bakelite binder e2 if it were permitted to reachthe beliebte. The bakelite 82 acts as an eective stop to prevent theliquid within the tube from reaching the asphaltum since the asphaltumis subject to attack by this liquid.

When an excessively large current flows through the fuse the i'use link27 melts and substantially simultaneously therewith'thehigh resistancestrain wire 26 likewise melts. Thev terminal 30 is then snapped downwardby the spring 60 thereby drawing an are between the too oi the terminaland the remaining portion of the :fuse: link extending out of the bailmem ber lo. The liquid director 40 is spaced from the terminal member 31and is drawn downwardly therewith during its descent. As may be seenfrom the drawing, the liquid director 40 is provided with a conicalopening having its largest diameter bottommost. As the liquid directormoves downwardly with the terminal 30` the liquid within the tube 1squirts through the conical opening, past the space between the lithluid director and the terminals, into the region or the arc. Thm`produces a violent agitation oi? the liquid in the region'of the are,constantly directing fresh, cool liquid into the arc to quicklyextinguish it.

the circuit interruption a certain amount ci the liquid within the tubeis voiatilised.

Since the gases that are formed by the volatilise.-s

tion of the liquid occupy a greater space than was occupied hy theliquid from which the gases were formed, it is apparent that thepressure within the tube l will increase. When the fuse functions tointerrupt a very severe short-circuit amount oi ses generated becomesappreciable and unless means is provided for permitting the escape oi.the gas the resulting pressure will shatter the glass tube and splashthe contents and the broken glass around everything. To avoid such anoccurrence the cap il@ is not secured to the upper ierrule very tightly,so that when the pressure within the tube becomes excessive the cagowill be blown oil, thus permitting the e escape of the gases generated.Thus the shatterexplosion chamber in the ferrule 2 above the splitcollar lo. Consequently the initial explosive eiieot upon blowing issubstantially confined to the chamber above the collar 70 with theresult on short-circuit or very heavy overload the vent cap blows offbefore any extensive pressure L can develop in theglass tube. When thearclng terminal is drawn down into the liquid the collar 7o is to riseand prevents any excessive pressure within the glass tube as the arcingternitz nal .is wn down into the liquid. Even the initial ei; osiveeffect in the chamber above the collar lo 'm not transmitted through theici-rule 5i and through the wall of the tube i, because in use theexternal shoulder ineens on the ferrule 2 is preferably seated againstthe iuse clip or an ad jacent shoulder and the explosive eiect throughthe ferrule is taken up by this seating engagen meut a d not transmittedto the wall of the tube.

lip-o: violent blowing ci the fuse, which results in removal oi the copto, the upper terminal or the usejincluoling bridge i3, is freelyexpelled, inasmuch ss the release or" 'the terminal from the spring'tension which held it in position releases the which it had upon. theinner walls ci. the ierrule. 'he fuse may be restored for service byunscrewing the sleeve 3o from the stud 50 and relu placing the same witha fresh unit, including new sleeve 3o, liquid. director 40, bridge i3shuntina conductor 25, which are then readily dropped into place. Thesplit washer '26, which liti likewise was expelled by is replaced byanew one. The liquid is replaced with a fresh charge and the devicesealed.

While I have herein shown and described a preieri-ed embodiment of myinvention it is to be understood that the invention is not limited totheprecise construction herein shown but is capable of various modications,the fuse here shown being merely illustrative oi the invention.

What I consider new and desire to secure Letters Patent is:

1. In a device oi! the class described, the combination ot a tubularcasing, a terminal. ferrule on the casing, a movable terminal Within thecasing, a coiled spring normally under 'tension and connected with themovable terminal, a fuse connected between the movable terminal and theferrule and means for anchoring said movable terminal under the tensionof said spring, said anchoring means having universal mounting on saidIerrule and including a bail member supported at a single point and inturn supporting the movable terminal and the fuse.

2. In combination, a trame, a terminal, a fuse connected between saidterminal and said frame,

operation oi the fuse,

`a spring connected to said terminal and an anchor for said terminalincluding a bail member having universal. mounting on said frame and astrain wire supporting the terminal from said bail member.

3. A circuit interruptor comprising a casing, a terminal membersupported within the casing by means including a universal mounting, aspring exerting a pull on the terminal, a severable connection includinga fuse element disposed between the terminal Aand the universal mountingand a strain wire for relieving the fuse of the Spring tension.

4. A circuit interrupter comprising a casing, a bridge member supportedin the casing, a terminal'member suspended from the bridge member by asever-able connection including a strain wire and a single pointsuspension having freedom of motion in all directions, said strain wirebeing severed upon the operation of the device to interrupt the circuit,spring means for rapidly separating the terminal from the supportingbridge upon the severing of the circuit, arc quenching liquid withinthe'casing, and a liquid director carried by the terminal for directingthe liquid .to the point of circuit interruption upon movement of theterminal under the action ci the spring. 1

5.' -A fuse having a terminal member. a sleeve into which the terminalmember is threaded, a bridge member for `supporting the sleeve andthereby supporting the terminal member, a joint permitting universalmovement of the sleeve with respect to the supporting bridge member, anda fusible element establishing an electrical connection between theterminal and the bridge member and located between them.

E. A fuse comprising a hollow supporting inember having embedded thereina connecting conductor, a fuse element,and a strain wire; and a terminalsuspended from the supporting member by the strain wire, the other endof the fuse being connected to the terminal, thereby establishing acircuit between the terminal and the connecting conductor.

7. A fuse comprising a hollow supporting member having embedded thereina. connecting conductor, a fuse element, and a strain wire; a terminalsuspended trom the, supporting member by the strain wire, the other endof the fuse element being connected to the terminal, therebyestablishing a circuit between the terminal and the connectingconductor, and means for pulling the terminal member away from thesupporting member.

8. A fuse comprising a hollow supporting member having embedded thereina connecting conductor, a ruse element, and a strain wire; a terminalsuspended from the supporting member by the strain wire, the other endof the fuse element being connected to the terminal, therebyestablishing a circuit between the terminal and the connectingconductor, means for pulling the terminal member away from thesupporting member, and a point support for the supporting member wherebythe same has a limited degree of universal motion.

9. A fuse comprising a hollow supporting member having embedded thereina connection conductor, a fuse element, and a strain wire; a terminalsuspended from the supporting member by the strain wire, the other endof the fuse element being connected to the terminal, therebyestablishing a circuit between the terminal and the connectingconductor, and a joint support for the supporting member whereby thesame has a limited degree of universal motion.

l0. A fuse including a conducting cylinder having a groove therein, anda fuse wire embedded in the groove and rigidly held in place bycompression of the sides of the grpove thereon.

11. A fuse including a conducting cylinder having a longitudinal groovetherein extending up to the end ci the cylinder, and a fuse wireembedded in the groove and rigidly held in place by compression of thesides of the groove thereon.

12. In combination, a terminal having a plurality of grooves therein,wire supporting means for the terminal extending into at least one ofthe grooves, and a fuse wire extending into another one of the grooves,said fuse wire and said wire supporting means being secured in place bycompression of the terminal to force the side walls of the groovestogether.

13. A fuse comprising a casing, a fusible element in the casing, a capfor the casing extending over the outer periphery of the casing, saidcap being adapted to be blown oi! ot the casing upon an abnormal blowingof the fuse, and an air tight seal between the cap and the outerperiphery of the casing, said seal comprising a plastic compound toprevent the leakage of the contents o! the tube and a dissimilarcompound to prevent the entrance 'oi moisture into the tube.

i4. A fuse comprising a casing, a fusible element in the casing, a capfor the casing, said cap being adapted to be blown otr of the casing byan abnormal blowing of the i'use, a body of arc quenching liquid withinthe casing for extinguishing the are of the fuse, and a seal between thecap and the casing for sealing the same, said seal comprising a compoundimpervious to the action of the are quenching liquid on the inner sideof y the seal for preventing the outward creepage of 1U) the liquid, anda compound impervious to moisture on the outer side of the seal forpreventing the entrance o! moisture into the casing.

i5. A ruse comprising a casing, a fusible element in the casing, a capfor the casing, said cap being adapted to be blown oil.' of the casingby an abnormal blowing of the fuse, a body of arc` quenching liquidwithin the casing for extinguishng the arc of the fuse, and a sealbetween the cap and the casing for sealing the same. said 150 theoutward creepage of the liquid, and an asphal-= tum compound imperviousseal comprising a phenol condensation compound impervious to the actionof the arc quenching liquid on the inner side of the seal for preventingto moisture on the outer side of the seal for preventing the entrance ofmoisture into the casing.

18. A terminal member comprising, ceiving portion,

having a central opening therethrough, a bridge bar extending acrosssaid opening, and a terminal' suspended from the bridge bar by a singlepoint suspension having freedom of "motion in. all ditablishing therections.

i8. fuse device having a retraction spring and a universal su port foranchoring said spring and a bail member resting thereon.

is. A fuse comprising a 'tubular member hav= ing contact ferrules at itsupper and lower ends, means including a fuse link for maintaining anelectrical connection between the ferrules, spring the connection,electrical contact with the upper ferrule for es` tablishing theelectrical circuit between the fuse link and the upper ferrule, saidlast named means including a conductor electrically connected to thefuse link, and a transverse member extendresting on the conductor withinthe `ici-rule and maintaining the pressure contact between the conductorandthe ierrule through the action of said spring.

\ 20. A fuse comprising a tubular member naving contact ferrules at itsupper and lower ends, maintaining an electrical connection between theferrules, spring means normally under tension and. released upon gap inthe connection, said upper ferrule having a shoulder therein, and meansmaking a pressure electrical contact with the upper ferrule for es-1electrical circuit between tlie fuse link and the upper ferrule, saidlast named means including a conductor electrically connected to thefuse link, and a transverse member extend= ing across and resting on theshoulder Within the ferrule and maintaining the pressure contact betweenthe conductor and the fel-rule through the action of said spring, saidfuse link and spring being supported from the transverse member.

vleased upon blowing of the iuse link and the upper ferrule, said lastnamed means including a transverse including a transverse memberextending across and resting Within the icrrule and maintaining thepressure contact through the action of said spring, said fuse and springmeans being supported from said transverse member by means including auniversal mounting.

23. .fi fuse comprising a tubular member having contact ierrules at itsupper and lower ends, means including a fuse iinl for maintaining anelectrical connection between the ferrules, spring means normally undertension and released upon blowing ci the fuse link to produce anextended gap in the connection, said upper ferrule having a shouldertherein, and means making a pressure electrical 'contact with the upperierrule for establishing the electrical circuit between the fuse linlrand the upper ferrule, said last named means including a transversemember extended across and resting on the shoulder within the ferruleand maintaining the pressure contact through the action of said spring,said transverse member extending upwardly from the shoulder and bearingagainst the inner side Walls of the upper fer rule, said fuse and springmeans being supported from said transverse member by means including auniversal mounting.

24. ./-l fuse comprising a tubular member hav ing a contact ferrule atits upper end, a fuse linie, spring means normally under tension andrelink to produce an extended gap in the circuit through the fuse, andmeans making a pressure electrical contact with the ierrule iorestablishing an electric circuit between the fuse lint". and theferrule, said last means including a transverse member eiatenclingacross and resting upon a shoulder with in the ierrule maintaining thepressure conn tact through the action of said spring, said transversemember making e. snug t within the fer rule and being arci-led upwardlyfrom said snoula der with the fuse and spring means located below thetransverse member and supported therefrom and pulling the same againstthe shoulder.

25. i fuse comprising al tubular member liavlfing a contact ierrule atits upper end, a fuse iinlsz, spring means normally under tension and released uponblowing oi the fuse'link to produce an extended gap in thecircuit through the fuse, and means making a pressure electrical contactwith the ferrule for establishing an electric oir cuit between the fuselink and. `the ferrule, said last named means including a transversemientol ber extending across and resting upon a shoulder within theierrule and maintaining the pressure Contact through the action of saidspring, said izo transverse member extending upwardly from said shoulderwith the fuse and spring means located below the transverse member andsupported therefrom by means including a universal mounting.

26. A fuse including a casing having a ferrule at its upper end, abridge member supported on the inner side of the ferrule, a fuse link, amovable terminal, means supporting said. movable terminal from saidbridge member, spring means pulling said movable terminal away from thebridge member and pulling said bridge member inward of the fuse casing,and a conductor extending a circuit between the 'fuse and the ierrule,said bridge member bearing on the end of said conductor and through theaction of the spring exerting a clamping action to clamp the conductoragainst the ferrule.

27. A fuse including a casing having a ferrule at its upper end, abridge member supported on the inner side of the ferrule, a fuse link, amovable terminal, means supporting said movable terminal from saidbridge member, said bridge member being upwardly arched from itssupport- A ed ends andsaid terminal being suspended from the crown ofthe arched portion, spring means pulling said movable terminal inwardlyof the casing and away from the bridge member, and a conductor extendinga circuit between the fuse and the Ierrule, said bridge member bearingon the end of said conductor and through the action of the springexerting a clamping action to clamp the conductor against the ferrule.

28. A fuse Iincluding a casing having a ierrule at its upper end, abridge member extending across the open end of the errule and supportedon the inside thereof with its ends against the inner verticalperipheral wall of the ferrule, means for drawing a gap in the circuitextending through the casing, said means including a spring held undertension and a fuse link for eiecting the release of the spring, saidspring exerting a pull on the bridge member, and a conductor forextending a circuit from the fuse link to the ferrule, the two ends ofthe conductor being interposed between the wall of the Ierrule and theopposite ends of the bridge member, whereby the pull of the spring onthe bridge' member produces a pressure contact between the conductor andthe ferrule.

29. A fuse including a casing having an open ferrule at its upper end,an upwardly arched bridge member extending across 'the open end of therei-rule and supported on the inside thereof, and means for drawing agap in the circuit through the casing, said means including a springheld under tension and a fuse link for effecting the release of thespring, said spring exerting its pull at the crown of the arched portionof the bridge and in a direction inward of the casing, the ends of thebridge member bearing against the inner side .of the vertical peripheralwaii ci the Ierrule whereby the ferrule holds the bridge member againstbeing iiattened by the action oi' the spring.

30. A fuse including a casing having an open ierrule at its upper end,an upwardlr,7 arched bridge member extending across the open end ci 'theferrule and supported on the inside thereof,

means for drawing a gap in the circuit through the casing, said meansincluding a spring held under tension and a fuse link for effecting therelease of the spring, said spring exerting its pali at the crown ci'the arched portion ci 4the bridge and in a direction inward or thecasing, the ends Vcontact Ierrules at its of the bridge member bearing'against the inner side of the vertical peripheral wall of the ferrulewhereby the ierrule holds the bridge -member against being flattened bythe action of the spring, and a closure for the open` end of the ferrulesubject to be opened by internal pressure.

31. A fuse comprising a tubular member having a contact ferrule at oneend, a conductor within the ierrule, means for establishing an electricconnection between the conductor and the ferrule, said means including atransverse member extending across and resting within the ferrule withits opposite ends upon both ends of the conductor and pressing saidconductor against the ierrule, a tension spring within the tubularmember mechanically connected to the transverse member by meansincluding a severable connection and exerting the pressure for pressingthe conductor against the errule, said severable connection between thespring and the transverse member including a fuse connected to theconductor whereby upon blowing o! the fuse the spring is retracted fromthe transverse member.

32. A fuse including a tube of insulation having contact ferrules at itsopposite ends, a iilling of arc quenching liquid within the tube, theupper ferrule having a shoulder therein at its upper end with the wallof the ferrule extending upward from said shoulder, a bridge memberextending across the errule and resting against the shoulder with theends o! the bridge member held in position by the upward extendingportion of the wall of the ferrule, means establishing an electricalconnection between the ferrules, said means including a connectingdevice suspended from the bridge member by a severable connectionincluding a fuse link, a tension spring secured at one end to the lowerferrule and at its other end to the connecting device and exerting apull on said device, the pull of the spring being transmitted throughthe severable connection and the bridge member to the shoulder on theupper ferrule, said connection'being severed upon blowing of the fuse,thereby permitting a retraction of the spring to produce an extended gapthrough the arc quenching liquid to promptly interrupt the circuitbetween the ferrules.

33. A fuse including a tube of insulation having opposite ends, afilling ot arc quenching liquid within the tube, the upper fel-rulehaving a shoulder therein at its upper end with the-wall of the ferruleextending upward from said shoulder, a bridge member extending acrossthe ferrule and resting against the shoulder with the ends of the bridgemember held in position by the upward extending portion of the wall ofthe tei-rule, means establishing an elec trical connection between theferrules, said means including a connecting device suspended :from thebridge member by a severable connection including a fuse link, a tensionspring secured at one end to the lower ierrule and at its other end tothe connecting device and exerting a pull on said device, the pull ofthe spring being transmitted through the severable connection and thebridge member to the shoulder on the upper ferrule, a conductorinterposed between the bridge member and the errule and pressed intoilrm contact with the ferrule by the pull of the Spring on the bridgemember, said conductor being electrically connected with the fuse link.said severable connection being severed upon blowing oi' the Jfuse,thereby permitting a retraction of the spring quenching liquid topromptly interrupt the'circuit between the ferrules.

34. In combination, a fuse housing having a metal lerrule with alongitudinal opening provided with an open end adapted to be releasablyclosed, a terminal member extending across the longitudinal opening ofthe ferrule and being' supported by engagement with the walls thereof, efuse under tension connected to the central part of said member, and alow resistance conductor connected at one point to the adjacent end ofVthe fuse, said conductor having an enti which is pressed by theterminal bar into goed electricel contact with the fermle to .form e.shtml;

bar and be expelled from the Ierabout. said terminal bar, said terminalconductor being free to rule on violent blowing of the fuse.

35. A replacement unit for :reconditioning a fuse, comprisngan archedterminal bar with a. :fuse link connected to the central part thereof,slmnting connections ci low resistence connected centrally to theadjacent end of the fuse and extending under the ends of the terminalbnr, and e, terminal member connected to the opposite' end of the fuseand lowing a, coupling portion for ready connection to or disconnectionfrom n,

tension spring. y

i MHQLS J.

less

vlio

